hostname

Checks that the value is a hostname (RFC 1123), for example api.example.com or localhost.

Error codes: WRONG_HOSTNAME, FORMAT_ERROR

Live example · edit rules or inputOpen in playground

rules

{
    host: 'hostname'
}

{
    host: 'hostname'
}

input

{
    host: 'my_server.example.com'
}

{
    host: 'my_server.example.com'
}

Invaliderrors

{
  "host": "WRONG_HOSTNAME"
}

Labels of 1–63 characters from A-Za-z0-9-, not starting or ending with -, separated by ..
At most 253 characters in total, no trailing dot.
A single label (localhost) passes. Labels of digits only pass too, except the last one: 192.0.2.1 and 123 give WRONG_HOSTNAME (RFC 1123, section 2.1). So a hostname is never an IPv4 address; use { or: ['hostname', 'ip'] } to accept both.
There is no list of top-level domains. Internationalized names pass only as punycode.

hostname ​